CUMACEA FEOM THE COPENHAGEN MUSEUM. 377 



species described below is strongly suggestive of the genus Psemlocuma, and, in fact, 

 almost the only character visible without dissection to forbid its inclusion in that 

 genus is the segmented endopod of the uropods. An affinity with the Diastylidae is 

 suggested by a number of small characters, of which the chief are the segmented inner 

 ilagcllum of the antennule, the modification of the antennular peduncle and of the 

 telson in the male, the triarticulate antenna in the female, the distally expanded 

 basis of the third maxilliped, and the biramous pleopods in the male. The sum 

 of these characters, however, does not remove the impression that the resemblance 

 to the Pseudocumidae is more than superficial and that the distinction between that 

 family and the Diastylidae is of diminishing importance. 



CoLUKOSTYLis PSEUDOCUMA, sp. n. (Plate XXXVI. figs. 23-36.) 



Description of adult Female. — Total length 2-1 mm. (larger specimens to 2-3 mm.). 



Carapace about two-sevenths of total length ; its vertical height two-thirds of its 

 length ; dorsal edge slightly curved. Pseudorostrum straight, acute, horizontal or 

 slightly raised. Antennal notch obsolete, antero-lateral corner rounded. Surface of 

 carapace marked with very shallow broad pits. The ocular lobe is shaped much as in 

 Pseudocuma longicornis. The eye is without pigment in the specimens examined. 

 The free thoracic somites are deeper than the carapace anteriorly, the pleural plates of 

 the third curved backwards so as to separate the third pair of legs widely from the 

 second. The abdomen is a little shorter than the cephalothoracic region. The telson 

 is about two-thirds as long as the last somite, obtusely pointed posteriorly, carrying 

 a very few minute setae but without spines. 



The antennules have the first segment of the peduncle longer than either the second 

 or third ; the outer flagellum is about equal to the last segment of the peduncle, of 

 tliree segments, the terminal very small ; the inner flagellum is about equal to the 

 first segment of the outer, also composed of three segments, the first and third minute. 

 The antennae are distinctly divided into three segments, the first bearing two setic, the 

 second and third one each. 



The mouth-parts resemble those of Pseudocuma. The mandible has about nine 

 spines. 



The third maxillipeds have the basis expanded at the distal end and slightly produced, 

 bearing on its distal edge a series of about four plumose setae. 



First pair of legs broken ofi" in all the specimens seen. 



Second legs with the basis about three-fourths as long as the distal segments 

 together ; dactylus short, not twice as long as propodus. 



Third and fourth pairs of legs with the basis shorter than the distal segments 

 together, bearing near its base an exopod of two segments, not much less than half the 

 length of the segment from which it springs. Last pair of legs not much shorter than 

 the preceding pair. 



